Answers

Rose of Sharon is generally taken to mean Hypericum calycinum, but is sometimes used to commonly refer to any of the Hypericums, so could you clarify which plant you actually mean please? One or two of them are slightly less hardy. You also haven't said where you want to plant it, which makes it a bit difficult to say whether it will do well or not.

Rose of Sharon is Hypericum, an evergreen shrub, however it can also be classed as semi evergreen .... i'm thinking in 'your' climate it could be the latter.
You may have to overwinter it in shelter which could mean having it potted so you can shift it about.